import matplotlib.pyplot as plt
import numpy as np
from test_4_00 import create_polar_system

# 创建极坐标系
fig, ax = create_polar_system(r_range=(0, 5))

# 固定的θ值
theta = 3*np.pi/4
color = 'r'

# 创建r值数组
r_values = np.linspace(0, 5, 100)

# 创建θ值数组（全部为固定值）
theta_values = np.full_like(r_values, theta)

# 绘制θ = 3π/4对应的曲线
ax.plot(theta_values, r_values, color + '-', linewidth=2.5, label='θ=3π/4')

# 添加图例
ax.legend(loc='upper right', bbox_to_anchor=(1.15, 1.15))

# 标记极点
ax.plot(0, 0, 'ko', markersize=6, label='极点')
ax.text(0.1, 0.3, 'O', fontsize=10, color='black')

plt.tight_layout()
plt.show()